tapering tubes?
Moderator: Mike Everman
tapering tubes?
I want to start fiddling with the creation of a "Bruno-O" high compression pulsejet. The only uflow models that show promise consists tapered tubes end to end. Anyone got ideas on how to make a tapered tube (1" id -> 0.5" id) about a half meter long?
I think that the engine will take some fiddling to get is to work, so I'm hoping for a really simple technique. Careful "squashing" of the tube was the only idea that I've had so far.
I think that the engine will take some fiddling to get is to work, so I'm hoping for a really simple technique. Careful "squashing" of the tube was the only idea that I've had so far.
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Re: tapering tubes?
how would you make one? a hammer, an anvil, and lots of patience
sounds like the tailpipe on the K-PT01b I built
http://www.pulse-jets.com/phpbb2/files/dsc01134.jpg
http://www.pulse-jets.com/phpbb2/files/dsc01041.jpg
http://www.pulse-jets.com/phpbb2/files/ ... nd_new.jpg
sounds like the tailpipe on the K-PT01b I built
http://www.pulse-jets.com/phpbb2/files/dsc01134.jpg
http://www.pulse-jets.com/phpbb2/files/dsc01041.jpg
http://www.pulse-jets.com/phpbb2/files/ ... nd_new.jpg
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Re: tapering tubes?
I think the best idea I ever saw posted on something like that was from somebody [probably Mark] who suggested visiting junk shops to find tapered tubular steel table legs. Of course, those will be almost a metre long, but you might readily find one that you can cut the proper piece out of. It depends, of course, on whether you feel you need precise dimensions or just something reasonably close. They will almost certainly be plated or painted, but I've never found that to be particularly troublesome when working with steel pieces.
If you live in or near a good-size city, just set aside a Saturday to go tour the shops - you probably already know where some of them are.
L Cottrill
If you live in or near a good-size city, just set aside a Saturday to go tour the shops - you probably already know where some of them are.
L Cottrill
Re: tapering tubes?
The table thing is sheer genius. The dimensions just need to be close enough for govt. work -- if the design is too sensitive to geometry, then it probably won't throttle, won't operate when its too hot or cold etc., etc.
I'll grab a table for long sections and maybe a chair for some shorter sections. If I can get a prototype running then I can go back and build it properly.
If a working engine ends up looking anything like the model, then I've noticed that tapered light poles seem to be just about the right dimension for a big engine ;). The pulses would be two 40 Hz waves (out of phase) with lots of harmonics -- one way to make the local papers, probably.
I'll grab a table for long sections and maybe a chair for some shorter sections. If I can get a prototype running then I can go back and build it properly.
If a working engine ends up looking anything like the model, then I've noticed that tapered light poles seem to be just about the right dimension for a big engine ;). The pulses would be two 40 Hz waves (out of phase) with lots of harmonics -- one way to make the local papers, probably.
Re: tapering tubes?
I thought it was some likeable British fellow, I can't remember who suggested or posted a picture of some table legs. I suggested some tall flared stainless steel lamps I saw in a large hardware store in the lighting section that had ceiling fans, tall and short lamps, etc.
Mark
Mark
Re: tapering tubes?
[quote="steve"]how would you make one? a hammer, an anvil, and lots of patience
To which I might add a template and a clear vision in your mind of where you want to wind up as far as form.
You might want to research the processes involved in forming.
Hank
To which I might add a template and a clear vision in your mind of where you want to wind up as far as form.
You might want to research the processes involved in forming.
Hank
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Re: tapering tubes?
I'd add the instruction a friend of mine said he had seen in the manual for a Japanese bike that arrived in kit form and had to be put together by the buyer:steve wrote:how would you make one? a hammer, an anvil, and lots of patience
"The building of this bicycle should be attempted only in the state of complete emotional balance."
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Re: tapering tubes?
LOL! As well as the running of it.
Mike Often wrong, never unsure.
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Re: tapering tubes?
I love those Chinese instructions too. I got them with my two lathes, and other things I have ordered. The writing is flowery and as if a child were trying to caution you ever so gently about a serious potential hazard should you botch the assembly and/or use the device after having one too many beers.
Something like "do not enjoy beer while lathe is spinning." It's a riot to read the well-intentioned but laughable warnings, the incongruity. Maybe something like this too, "electricity can be about, do not think of something else if wiring is suspected, memory in a capacitor may last ."
I should get out my manuals again.
Mark
Something like "do not enjoy beer while lathe is spinning." It's a riot to read the well-intentioned but laughable warnings, the incongruity. Maybe something like this too, "electricity can be about, do not think of something else if wiring is suspected, memory in a capacitor may last ."
I should get out my manuals again.
Mark
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Re: tapering tubes?
Most tables are about 30" or 32" high, so the legs would be slightly shorter than that.
Trig IS fun.
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Re: tapering tubes?
A guy I know just sent me the text he took of a German website. The Germans have started manufacturing the Raven powered hang glider. Since the guy does not speak German, he pushed the text through Babelfish. Here's what he got:Mark wrote:I love those Chinese instructions too. I got them with my two lathes, and other things I have ordered. The writing is flowery and as if a child were trying to caution you ever so gently about a serious potential hazard should you botch the assembly and/or use the device after having one too many beers.
Something like "do not enjoy beer while lathe is spinning." It's a riot to read the well-intentioned but laughable warnings, the incongruity. Maybe something like this too, "electricity can be about, do not think of something else if wiring is suspected, memory in a capacitor may last ."
I should get out my manuals again.
Mark
courtesy of www.babelfish.altavista.com:
Who didn't dream yet to fly independently of mountain or hoist with its hanging glider where always it wants? But not with the power saw in the neck, but with a quiet and nevertheless strong engine belt, which well processes to handle easy and is fully everyday life suited.
Start from the level, the engine turn off and in the thermionics circle. If nothing more goes, comfortably by e-starter the hanging glider engine to start and home fly. No aufwaendigen back getting actions.
A Sightseeing flight in the vacation, with an engine belt, which fits comfortably into the trunk. Walk-fly or simply, the homeland from air explore. Which kite flier didn't dream yet about it?
With the Raven all this is in a simple manner feasible. The engine belt has enough thrust, in order to start from the level with zero wind. It is a minimum drive, which hardly worsens the aerodynamics and flight characteristics of the hanging glider. Thus also long thermikfluege with this minimum system with fun are feasible.
The harness is a modern front A riser with camera, radio and seitentasche. In order to achieve as good-natured a flight characteristics as possible with takeoff and landing, consciously without a central suspension one did.
Hand gas, Choke, starter button, engine circuit breakers and propeller brake are ergonomically positioned at the control console at the pilot shoulder. The pilot has so at any time all controls before eyes and full control of its Drachenmotor.
Der Raven is in less than five minutes and due to its easy handling a very good-natured foot-startable UL system. Randy Haney, thereby a completely balanced engine harness succeeded to the technical designer and manufacturer of the Raven, at which each ambitionierte hanging glider pilot can have its joy.
Motorized kite flies in its Urspruenglichsten form.
Re: tapering tubes?
lol
I'm glad I asked the question - not only got an answer, but the thread has taken such an interesting turn
I'm glad I asked the question - not only got an answer, but the thread has taken such an interesting turn